Foundation for a structure and method of installing the same

ABSTRACT

A foundation (10) for a structure including a body (1) for insertion into a soil (2) in an insertion direction during installation, the body (1) having a toe (3) at its distal end. An array of nozzles (6) are provided at the distal end for jetting a fluid, with the nozzles (6) in the array being configured such that their fluid jets (7) are complementarily directed for generating a fluid stream (8) ahead of the toe (3) which flows in a direction perpendicular to the insertion direction to erode the soil below the pile toe.

The present invention concerns a foundation for a structure and a methodfor installing the same. In particular, the present invention concernsstructural foundations, such as piles, tubular piles, monopiles, jacketpiles, suction bucket/caisson foundations and suction anchors, skirtedfoundations, sheet walls, berthing dolphins, and other types oftemporary and permanent shallow or deep water foundations, that may beinserted into a soil for supporting structures such as buildings, walls,offshore structures, and wind turbines. The present invention isparticularly suited to offshore foundations, and more particularly toopen ended tubular foundation types, such as monopiles, jacket piles andsuction buckets, and most particularly to offshore wind turbinefoundations.

Structural foundations are typically installed by forcing the foundationinto the ground using a piling or hydraulic impact hammer to apply aseries of axial impacts for driving the foundation down into the soil inan insertion direction. Once installed, the foundation is axiallysupported by the friction applied to the lateral surfaces of thefoundation's body and, to a lesser extent, the resistance to furtherpenetration at the foundation's toe.

With conventional installation techniques, the toe at the distal end ofthe foundation displaces soil as it is driven down. This compresses thesoil in the surrounding region. However, as the foundation is drivendeeper, and pressure increases, the forces required to continuedisplacing soil at the foundation's toe also increase. At the same time,the lateral surface area of the foundation in contact with the soilincreases, leading to an increase in the shear forces required toovercome the frictional resistance to driving. As a result, the bearingresistance increases as the foundation is installed deeper into thesoil.

In recent years, there has been a trend towards having larger monopileand other foundations, and this has exacerbated the above challenges oftheir installation. For example, higher impact forces and/or a highernumber of hammer strikes are required for pile driving largerfoundations. This in turn imposes significant failure resistancerequirements on the foundation. At the same time, the noise generated bythe larger impacts is also increased, which presents significantenvironmental and safety hazards.

In view of the above, various methods and systems have been proposed formaking the installation of foundations easier. For example,electro-osmosis has been proposed as a mechanism to lower shaftresistance during pile installation by attracting pore water to thefoundation body. This thereby lubricates the interface between the soiland the foundation surface. However, whilst research in this areacontinues, electro-osmosis may not be suitable in all circumstances. Assuch, there remains a need for other methods and systems for reducinginstallation resistance during installation of a foundation.

The present invention therefore seeks to address the above issues.

According to a first aspect, there is provided a foundation for astructure comprising: a body for insertion into a soil in an insertiondirection during installation, the body having a toe at its distal end;and an array of nozzles provided at the distal end for jetting a fluid,wherein the nozzles in the array are configured such that their fluidjets are complementarily directed for generating a fluid stream ahead ofthe toe which flows in a direction substantially perpendicular to theinsertion direction.

In this way, the present invention provides a foundation that may beinstalled more easily. In particular, the generation of the fluid streamdriven by high-pressure jetting from the nozzles provides a highvelocity flow which erodes soil as it moves around a fluid channelformed in a plane ahead of the toe. As soil is eroded, coarse grains areaccumulated in the suspension, increasing its abrasiveness, and furtherenhancing erosion. The toe may therefore progressively advance into thecavity formed by the flowing fluid. At the same time, the excess soilsuspension caused by the persistent fluid influx is pushed upwardsthrough the gap between the foundation wall and the soil that is createdby the abrasive suspension flow. As such, soil particles are continuallytransported away from the installation front. Importantly, as the fluidflow is perpendicular to the installation direction, and thecomplementary configuration of the nozzles acts to enhance the speed ofthe fluid flow, the erosion of the fluid cavity walls is controlled andrapid. This contrasts with conventional jetting techniques which rely onhigh-power vertical jets to mechanically cut into and breakup the soil.Embodiments of the invention therefore allow for both improvedinstallation speed and retention of the surrounding soil structure forproviding a more stable support for the foundation once installed.

In embodiments, the fluid stream forms a fluid channel ahead of the toein a plane perpendicular to the insertion direction by eroding soil asthe fluid flows through the fluid channel in the direction perpendicularto the insertion direction.

In embodiments, soil is progressively eroded from the wall of the fluidchannel as the toe advances in the insertion direction duringinstallation.

In embodiments, the nozzles in the array are configured for generatingthe fluid stream flowing in a cyclic path in a soil region ahead of thetoe. In this way, the fluid stream may form a continuous loop, allowingthe fluid flow to be driven around by the nozzles in the respectivearray at a high velocity, with each nozzle feeding into the streamproduced by the preceding nozzles.

In embodiments, the cyclic path is a circumferential path coaxial withthe body. In this way, the fluid channel cavity formed by the fluidstream is aligned with the foundation's body for creating the spacebetween the soil and the body as the foundation advances in theinstallation direction.

Preferably, the foundation is provided as a hollow foundation. Morepreferably, the foundation is a hollow pile foundation. Even morepreferably, the foundation is a monopile. For example, the monopile maycomprise a hollow tubular body.

In embodiments, the foundation further comprises a second array ofnozzles provided at the distal end, wherein the nozzles in the secondarray are configured such that their fluid jets are complementarilydirected for generating a second fluid stream ahead of the toe whichflows in a direction perpendicular to the insertion direction andopposite to the first fluid stream. In this way, a second array ofnozzles may be provided with their jetting thrust being applied in anopposite direction to the thrust applied by the first nozzle array. Thisthereby counteracts the torsional moment that would otherwise be appliedby jetting in an uniform direction. At the same time, the generation ofa second stream allows a wider cavity area to be formed for creatingspace between the soil and the foundation body.

In embodiments, the first array of nozzles is provided on an interiorside of the body for generating the first fluid stream in a path in linewith an interior lateral surface of the body, and the second array ofnozzles is provided on an exterior side of the body for generating thesecond fluid stream in a path in line with an exterior lateral surfaceof the body. In this way, the angle of the nozzles in each of the firstand second arrays may be respectively directed for creating spacebetween the soil and the interior and exterior lateral surfaces of thefoundation body.

In embodiments, a fin provided at the distal end for separating thefirst fluid stream from the second fluid stream. In this way, efficiencymay be improved as less jetting energy is dissipated by the turbulentinterface between the opposing streams. At the same time, the respectivenozzles of each of the arrays may be angled more closely together,thereby providing a narrower combined fluid channel cavity, and in turnallowing the soil structure surrounding the foundation body to be betterpreserved.

In embodiments, the foundation further comprises a manifold at thedistal end of the foundation and wherein the nozzles are mounted to themanifold for being fed fluid thereby. In this way, pressurised fluid maybe fed to the nozzles at the distal end of the foundation, with theshape of the manifold defining the shape of the path of the fluidchannel cavities formed during jetting. That is, the shape of themanifold in a horizontal plane determines the shape of the fluid channelin a horizontal plane. At the same time, the pressurised fluid appliedacts to maintain the shape of the interior bore within the manifolditself.

In embodiments, the nozzles are directed downward in the range of 1-40degrees about the radial axis from the tangential direction. Preferably,the nozzles are directed in the range of 10-30 degrees from thetangential direction. In this way, rather than being directed into thesoil ahead of the toe, the jetted fluid from nozzles in each array isdirected diagonally down for driving the fluid suspension flow in alateral plane. For example, for round foundations, the fluid suspensionflow is driven circumferentially. In embodiments, the nozzles aredirected in the range of −10 to +10 degrees about an axial axis from thetangential direction.

In embodiments, the nozzles are distributed around the perimeter of thetoe. In this way, the velocity of the fluid stream formed by the fluidjetting may be maintained throughout the fluid circuit for providinguniform soil erosion.

In embodiments, the foundation further comprises a pressurised fluidsupply for supplying pressurised fluid to the nozzles. Preferably, thispressurised fluid supply is in excess of 10 bar relative to the ambientfluid pressures, and more preferably above 100 bar relative to theambient fluid pressures, and even more preferably above 200 bar relativeto the ambient fluid pressures.

In embodiments the nozzles have a diameter of 1.5-5 mm. It will beunderstood that, the larger the nozzle diameter, the greater the influx.In a preferred embodiment, the nozzles have a diameter of 2.8 mm. Insuch embodiments, the fluid may be supplied at a pressure of around 250bar. Such embodiments may be implemented with a 9 m diameter monopilehaving two rows of nozzles pointing in the different directions and eachnozzle being spaced 15 cm apart.

In embodiments, the foundation further comprises a controller forcontrolling one or more of: an installation speed, a ballast weight, anda fluid pressure of fluid supplied to the nozzles.

Preferably, the fluid comprises water. The fluid may be, for example,seawater, or an aqueous solution or suspension. In this respect, acontroller may be provided for controlling the pressure, flow rateand/or composition of the fluid delivered through the nozzles.

In embodiments, the foundation may further comprise an additive deliverysystem for delivering additives to the fluid stream. For example,abrasion increasing additives may be introduced into the fluid flow forenhancing soil erosion. Such additives may be introduced into the fluidsupply or using a separately delivery path. For example, it is envisagedthat abrasion increasing additives, such as coarser grains, fine gravel,or steel shot, could be deposited on the seabed near the pile wallbefore or during installation. Such additives may then trickle down theannulus to the erosion front as it progresses downwards for enhancingsoil erosion.

According to a second aspect of the present invention, there is provideda method of installing the above foundation, where the method comprises:inserting the toe into the soil; supplying the fluid to the array ofnozzles to jet fluid for generating the fluid stream ahead of the toewhich flows in a direction perpendicular to the insertion direction; andcontrolling movement of the body in the insertion direction to maintainthe formation of a fluid channel by the fluid stream as the toe advancesin the insertion direction.

In embodiments, the method further comprises the step of supplying thefluid to the second array of nozzles for generating the second fluidstream ahead of the toe which flows in a direction perpendicular to theinsertion direction and opposite to the first fluid stream.

Illustrative embodiments of the present invention will now be describedwith reference to the accompanying drawings in which:

FIG. 1 shows a cross-sectional view of a distal end of a foundationaccording to a first embodiment of the invention;

FIG. 2 shows an enlarged isometric view of a section of the fluidmanifold shown in FIG. 1 during fluid jetting;

FIG. 3 shows a cross-sectional plan view of a section of one array ofnozzles and the associated fluid flows in the embodiment shown in FIG. 1;

FIG. 4 shows a schematic illustration for explaining the jetting anglesof the nozzles;

FIG. 5 shows a sequence of the foundation of the foundation shown inFIG. 1 being installed; and

FIG. 6 shows a cross-sectional view of a distal end of a foundationaccording to a second embodiment of the invention.

FIG. 1 shows a cross-sectional view of the distal end region of afoundation according to a first embodiment of the invention. In thisembodiment, the foundation 10 is a monopile.

The foundation 10 comprises a hollow tubular body 1 having an exteriorlateral surface, and an interior lateral surface that defines aninterior cavity in the form of a bore. The distal end of the body 1forms a toe, which comprises a manifold 3 for feeding jetting fluid to aplurality of nozzles 6. The manifold 3 is fed by a pressurised fluidsupply (not shown) which delivers pressurised fluid to the distal end ofthe foundation 10, for example, from a pump provided on a nearbyinstallation vessel. Typically, the fluid supplied through the manifold3 is seawater.

The nozzles 6 are each supported on a lateral extension 5 which extendsout from the manifold 3 and includes an internal fluid pathway 4connecting between the interior of the manifold 3 and the outlet of eachnozzle 6. As such, pressurised fluid from the manifold 3 is jetted outthrough the nozzles 6.

In this embodiment, the nozzles 6 are arranged in two arrays, with aninterior set of nozzles 6 a provided on the interior lateral surfaceside of the body 1 and an exterior set of nozzles 6 b provided on theexterior lateral surface side. Each array of nozzles 6 arecircumferentially distributed around the manifold 3 so that they arespaced evenly around the distal end of the body 1. In this respect, FIG.2 shows an enlarged isometric view of a section of the fluid manifoldshown in FIG. 1 during fluid jetting. In this figure, two of the set ofexterior nozzles 6 b are most visible, with backs of the lateralextensions 5 for the set of interior nozzles 6 a being visible on theopposing side. As shown, the nozzles 6 within each array are angled todirect their fluid jets 7 diagonally downward and in the direction ofthe stream of the adjacent fluid jet. As such, all the nozzles 6 withineach of the interior and exterior arrays are uniformly angled in acomplementary configuration.

The above described configuration is shown more clearly in FIG. 3 whichshows a cross-sectional plan view of a section of one array of nozzles 6and the associated fluid flows generated thereby. It will be understoodthat there is also a flow going the opposite direction generated by theother array of nozzles. As shown, when pressurised fluid is supplied viathe manifold, each nozzle 6 produces a fluid jet 7. As the jetted fluidtravels diagonally down and further away from each nozzle 6, it spreadsand dissipates into the fluid suspension below the toe of thefoundation. The diagonal angling of the fluid jets 7 by the nozzles 6means that each jet, rather than cutting into the soil below thefoundation, feeds diagonally into the fluid suspension beneath theadjacent nozzle 6. As such, in use, this drives the fluid suspension ina plane substantially perpendicular to the insertion direction andthereby generates a high velocity circulating fluid stream 8 below therespective array of nozzles. This stream 8 flows in the jettingdirection in a path defined by the manifold 3. In embodiments, flowvelocities of 30 m/s may be generated. Accordingly, a high-speedcirculating fluid annulus is created by each array of nozzles 6, withthe fluid annuluses being coaxial with the foundation body 1. As shownin FIG. 2 , the interior and exterior nozzle arrays 6 a,6 b have nozzlesangled in different directions, and therefore their respective fluidstreams 8 a,8 b will also flow in opposite directions. Thisconfiguration in which opposing flows are generated acts to counteractthe torsional moment forces that would otherwise be applied to thedistal end of the foundation body 1 if the jetting thrusts from all thenozzles were directed in the same rotational direction.

As shown in FIG. 1 , in this embodiment, the interior and exteriornozzles 6 a,6 b are also angled slightly outward, away from each other,so that the fluid streams 8 a,8 b generated thereby are separated. Thatis, the nozzles are angled so that a nib 21 of the soil 2 below themanifold 3 remains between the two streams 8 a,8 b, which thereby avoidsinterference between them.

FIG. 4 shows a schematic illustration for explaining the jetting anglesof the nozzles in further detail. As shown, the foundation body 1defines an axial axis 21 which is coincident with the insertiondirection of the foundation. Perpendicular to this is the radial axis 22of the body 1, and the tangential direction 23 is also shown. In thisembodiment, the nozzles are angled in a jetting direction 24 by ajetting angle 25 that is 20 degrees below the tangential directionrotated about the radial axis 22. In other embodiments, the jettingangle 25 may be 0 to 40 degrees and preferably 10 to 30 degrees. Asmentioned above, the nozzles may also be angled slightly outward orinwardly, for example by an angle of −10 to +10 degrees about the axialaxis 21.

In use, as shown in FIG. 1 , particles 9 from the soil will becomesuspended in the fluid streams 8 a,8 b as the foundation body 1 isdriven into the soil. Accordingly, the fluid streams 8 a,8 b contain asuspension of abrasive soil grains, which flow at high speed in twoconcentric rings with opposing flows formed by the interior and exteriornozzle arrays 6 a,6 b. As such, the fluid streams 8 a,8 b, acceleratedby the fluid jets 7, have an abrasive effect on the soil 2 below,causing further soil particles to be broken away from the walls of thefluid channel. This has the effect of maintaining the space for thefluid streams 8 a,8 b as the toe of the foundation 10 advances deeperinto the soil 2. As a result, the soil 2 is rapidly eroded away ahead ofthe foundation 10, allowing the foundation 10 to move downward moreeasily through the soil.

In this connection, FIG. 5 shows a sequence of the foundation 10 beinginstalled in an offshore location. As shown in FIG. 5(a), the foundation10 is lowered through the water 10 so that its distal end inserts intothe soil 2. Prior to engaging with the seabed, the fluid jets 7 arestarted, albeit at a relatively lower pressure, such as 50 bar. Thisinitial jetting flow prevents soil from entering the jetting system.After the foundation's toe engages with the seabed, it penetrates downto an initial depth under its own weight. This depth may be, forinstance, around 2 meters.

Once the initial depth is reached, the fluid jetting pressure isincreased up to 300 bar. As shown in FIGS. 5(b) and 5(c), with thehigh-pressure jetting established, the toe of the foundation 10penetrates axially downward in an insertion direction through the soil2. As discussed above, the water jets act to accelerate the flow of thesoil suspension located below and around the toe of the body 1 formingat least one fluid channel cavity with high velocity circulating flowstreams. These streams 8 around the circumference of the toe region areloaded with abrasive soil grains in suspension and act to erode thewalls of the fluid channels. This thereby forms annuluses either side ofthe body 1, which separates the soil from the foundation's interior andexterior surfaces. The excess soil suspension caused by the persistentfluid influx through the jetting nozzles 6 also generates upward fluidflows through the gaps formed between the body's wall and the soil. Soilis thereby transported up the body of the foundation. These combinedeffects result in much lower frictional resistance during foundationinstallation.

The speed of insertion may be controlled by, for example, controllingthe rate that the foundation 10 is lowered by a crane 12. For example,an installation rate of 2 m/min may be maintained through this phase ofinstallation. Typically, the foundation's own weight will be sufficientto drive the toe downward. However, in some scenarios, a ballast (notshown) may be connected the proximal end of the foundation 10 to helpdrive installation.

In this connection, depending on the erodibility of the soil and thefoundation installation velocity, the size of the fluid channel cavitiesformed by the fluid jets 7 can be varied. If the installation velocityis too fast, the cavity can become too small such that the suspensionflow will eventually stall, and the erosion rate drops. In this case,the installation velocity can be reduced or stopped to allow for a newcavity to form and the suspension stream to develop. For instance, inuse, if a rapid increase in installation resistance is detected duringthe driving phase, the crane 12 may be used to stop installation andlift the foundation, for example by 10 cm, before restarting thelowering process of the pile. This thereby lifts the foundation tocreate space to re-establish the fluid streams 8, and thereby allowtheir abrasive effect to restart. This scenario may arise, for example,when conditions change from granular to a more cohesive soil duringinstallation. As the toe passes through the cohesive soil layer, theerodibility will be reduced, which could otherwise trigger a runawayeffect. By swiftly reducing the installation rate, stalling of thecircumferential flow may be avoided and, once the more cohesive layer ispassed, the installation rate can be gradually increased to return backto an optimal rate. It will be understood that if the installation rateis too fast for the crane 12 or the associated mechanisms, the jettingpressure may be reduced.

As shown in FIG. 5(d), once the foundation 10 reaches a predetermineddepth threshold slightly ahead of its target depth, the fluid jets 7 maybe turned off. For example, the predetermined depth threshold may be 30cm above the target depth. This thereby minimises the disturbance of thesoil at the target depth, allowing the foundation 10 to sink down to itsfinal target depth without overly weakening the soil structure in thisregion. The foundation 10 will resist further installation once thetarget depth has been reached. Once the insertion phase is completed,the soil 2 will relax to refill the space formed by the fluid streams.As shown in FIG. 5(e), a test load 13 may then be applied to verify theinitial axial load bearing capacity of the foundation 10. Over time, theaxial load bearing capacity of the foundation will progressivelyincrease as the load cycles from wave loading act to re-compact the soilin the annulus formed by the fluid streams.

FIG. 6 shows a cross-sectional view of a distal end of a foundationaccording to a second embodiment of the invention. This secondembodiment is substantially the same as the first embodiment, but thetoe of the foundation 10 is further provided with a fin 31 for dividingthe interior and exterior fluid streams 8 a,8 b. The fin 31 is used toseparate the opposing suspension fluid streams for avoiding interferencebetween them. This may thereby allow the respective nozzles of each ofthe arrays to be angled more closely together, thereby providing anarrower combined fluid channel cavity. This may allow the soilstructure surrounding the foundation body to be better preserved. At thesame time, it also provides for increased efficiency since less jettingenergy is dissipated by the turbulent interface between the opposingstreams.

It will be understood from the above that the inventive arrangementsdisclosed herein allow a foundation to be installed into the soil moreeasily. This reduces cost and allows installation noise to be minimised.

In this connection, with embodiments of the present invention, the soilfailure mechanism at the foundation toe can continue throughout the pileinstallation process as the foundation penetrates deeper. As such, theneed for pile driving or large ballasts to reach target installationdepths are avoided. After the foundation has been installed to therequired depth, the fluid jetting system may be turned off to allowwater to drain from the soil around the foundation body. The suspendedsoil particles will then settle to form a sediment which may compactover time through cyclic shake down effects, thereby restabilising thesoil strength.

Importantly, as the fluid jets are used to form fluid streams whicherode the soil, rather than directly cutting into the soil themselves,the structure of the soil outside the formed fluid channels is largelyundisturbed, with the suspension pressure acting to stabilize theadjacent soil. This soil is therefore able to maintain its structure forsupporting the foundation. This contrasts with conventional liquidexcavation techniques where a body of soil is cut into using pressurisedliquid to excavate space for a foundation. With this type ofconventional methodology, soil is removed in an uncontrolled manner, andthe excavated site is effectively refilled with reclaimed soil once thefoundation is in place. However, as the soil re-filling the space isnewly located, it has little developed structure and will therefore beinherently weaker as a result.

It will be understood that the embodiments illustrated above showapplications of the invention only for the purposes of illustration. Inpractice the invention may be applied to many different configurations,the detailed embodiments being straightforward for those skilled in theart to implement.

For example, it will be understood that by adjusting the jettingdirection of the nozzles, the location and shape of the fluid channelformed beneath the toe can be adjusted. For example, by locating thenozzles on the inside of the foundation, the fluid cavity will beshifted more towards the inside of the foundation body. Conversely, bylocating the nozzles on both the interior and exterior sides, andpointing them slightly away from the foundation wall, a wider cavity maybe created by the suspension flow, or two individual cavities may beformed, as shown in FIG. 1 .

Furthermore, in some embodiments, additives may be added to the fluidstreams formed at the toe of the foundation, for instance by introducingthem to the fluid supply or separately using an additive deliverysystem. For example, an abrasive additive may be used to introduce amore coarse/angular material for improving the abrasiveness of the fluidstreams. This may be advantageous for tackling soil types which do noteasily erode, such as silt, clay, chalk, soft bedrock. Grout may also beintroduced towards the end of the installation process for improving thein-place performance of the foundation.

It will also be understood that additional mechanisms and systems may bealso used in combination with the described fluid jetting system forfurther reducing driving resistance. For instance, the foundation mayfurther incorporate electrodes for electro-osmosis. Furthermore, thefluid jetting system may work synergistically with the electro-osmosissystem.

Finally, although in the above illustrative embodiments, the foundationwas a monopile, it will nevertheless be understood that otherfoundations are also possible, such as bucket foundations.

1. A foundation for a structure comprising: a body for insertion into asoil in an insertion direction during installation, the body having atoe at its distal end; and an array of nozzles provided at the distalend for jetting a fluid, wherein the nozzles in the array are configuredsuch that their fluid jets are complementarily directed for generating afluid stream ahead of the toe which flows in a direction substantiallyperpendicular to the insertion direction.
 2. A foundation according toclaim 1, wherein the fluid stream forms a fluid channel ahead of the toein a plane perpendicular to the insertion direction by eroding soil asthe fluid flows through the fluid channel in the direction perpendicularto the insertion direction.
 3. A foundation according to claim 2,wherein soil is progressively eroded from the wall of the fluid channelas the toe advances in the insertion direction during installation.
 4. Afoundation according to claim 1, wherein the nozzles in the array areconfigured for generating the fluid stream flowing in a cyclic path in asoil region ahead of the toe.
 5. A foundation according to claim 4,wherein the cyclic path is a circumferential path coaxial with the body.6. A foundation according to claim 1, further comprising a second arrayof nozzles provided at the distal end, wherein the nozzles in the secondarray are configured such that their fluid jets are complementarilydirected for generating a second fluid stream ahead of the toe whichflows in a direction perpendicular to the insertion direction andopposite to the first fluid stream.
 7. A foundation according to claim6, wherein the first array of nozzles is provided on an interior side ofthe body for generating the first fluid stream in a path in line with aninterior lateral surface of the body, and the second array of nozzles isprovided on an exterior side of the body for generating the second fluidstream in a path in line with an exterior lateral surface of the body.8. A foundation according to claim 6, further comprising a fin providedat the distal end for separating the first fluid stream from the secondfluid stream.
 9. A foundation according to claim 1, further comprising amanifold at the distal end of the foundation and wherein the nozzles aremounted to the manifold for being fed fluid thereby.
 10. A foundationaccording to claim 1, wherein the nozzles are directed downward in therange of 1-40 degrees about the radial axis from the tangentialdirection.
 11. A foundation according to claim 1, further comprising apressurised fluid supply for supplying pressurised fluid to the nozzles.12. A foundation according to claim 1, further comprising a controllerfor controlling one or more of: an installation speed, a ballast weight,and a fluid pressure of fluid supplied to the nozzles.
 13. A foundationaccording to claim 1, further comprising an additive delivery system fordelivering additives to the fluid stream.
 14. A method of installing afoundation according to claim 1, the method comprising: inserting thetoe into the soil; supplying the fluid to the array of nozzles to jetfluid for generating the fluid stream ahead of the toe which flows in adirection perpendicular to the insertion direction; and controllingmovement of the body in the insertion direction to maintain theformation of a fluid channel by the fluid stream as the toe advances inthe insertion direction.
 15. A method according to claim 14, furthercomprising the step of supplying the fluid to the second array ofnozzles for generating the second fluid stream ahead of the toe whichflows in a direction perpendicular to the insertion direction andopposite to the first fluid stream.